Dying cories

[Snowfire]

I have a 2 year old 110l tank with good filtration. I had some cories when the tank was pretty new, they only lasted about 6 months but I put that down to beginner mistakes.
I bought some new bronze cories a couple of weeks ago as I missed the ones I had before. I bought 6 thinking that would be a decent number but the following day 3 had died! The rest of my fish were fine & water test showed ammonia-0 nitrite-0 nitrate- 15 and pH-6.8.
I did a pwc of 50% to reduce the nitrates but the following day another 1 had died. I phoned lfs who asked me to bring in a water sample and they gave me a credit note for the 4 I had lost. The rest of tgeir stock looked fine. I decided to wait a while before adding more and sadly lost another a few days later. So then I was left with one
Obviously I didn't want to leave him on his own so after 2 weeks, a couple of decent pwcs and some nice new plants, I thought I should try again.
On Friday I got the 4 cories with my credit note, spent ages acclimatising them and they seemed fine. Yesterday morning, dead cory! Water test: ammonia-0 nitrite-0 nitrate-5 pH-6.8.
I did a pwc but they just weren't acting like cories
Today I've lost another so back to 3. I just don't get it!

 

[KaylNeko]

Try a different store? Sounds like weak stock. I'm assuming you acclimated them to your water before turning them loose, not just floated the bag. Otherwise, I'd start suspecting shock.

 

[absolutangel04]

Yeah, assuming that you acclimated them, I agree that it sounds like weak stock. There are some stores I don't go to anymore because about 50-75% of the fish I get from them tend to drop dead for no apparent reason within the first couple of months.

 

[Snowfire]

I floated the bag, gradually adding several cups of water for over an hour before releasing them. The lfs is only 4 miles from me and they have the same water supply so I doubt the water chemistry could be that different. They seemed fine the first day, shoveling through the sand and actively swimming. If it were weak stock, wouldn't they be dying in the store? The girl in the lfs said it was the same stock they had for weeks. I just don't understand, maybe I'm just not supposed to have cories

 

[absolutangel04]

No offense to the girl at the store, but she may not know exactly how many they got in and if any died. I do not see any issue with your tank or with the way you are introducing them, so I doubt you are the problem.
Do you know if the store has universal filtration in their tanks or if every tank has its own individual filter and is isolated?

 

[Snowfire]

The tanks are in sections, fresh, salt, brackish & whatever it is they do to Malawis (? Raise pH) each section has its own filter system. I bought some angels out of the same section for my large tank (the pink ones) whilst I was there and they're absolutely fine. It's a mystery!

 

[maestromad]

Next time you get fish from there test the water you will have a shock. I'm only 3 miles from my LFS but when I tested their water after getting my ottos their readings were off the chart!! Not good for the fishes esp if they aren't acclimated real slowly in my case

 

[Snowfire]

Arrgh, another one is dying!! I could only see 2 first thing this morning & now the other one looks like he's been attacked during the night. He's got a chunk of tail missing & breathing really fast. I'm trying to set up my hospital tank but don't think he's going to make it

 

[Sushisnake]

Next time you get fish from there test the water you will have a shock. I'm only 3 miles from my LFS but when I tested their water after getting my ottos their readings were off the chart!! Not good for the fishes esp if they aren't acclimated real slowly in my case

Excuse me for butting in but thanks for the tip. Good luck with the cories, Snowfire. I don't think they'd draw you if you weren't meant to have them.

 

[LyndaB]

What other fish are in this tank?

 

[Snowfire]

There is one angelfish, 6 black neons, 3 cherry barbs, 2 platies and 4/5 amano shrimp. Everyone else looks really healthy.

 

[Snowfire]

The filter is an aquis 750 external.

 

[LyndaB]

Corys are very sensitive and it's not unusual, from what I've heard and experience myself, to lose one without warning within the first month.

Since you are losing so many in an established tank, I would also believe the store has weak stock.

 

[Snowfire]

Thanks Lynda, I just hate seeing them die, I haven't lost fish like this before. It's so horrible but at least I can feel happy that I'm not doing anything wrong. On an up side, the little angels are loving their new home!

 

[KaylNeko]

Corys are very sensitive and it's not unusual, from what I've heard and experience myself, to lose one without warning within the first month.

Since you are losing so many in an established tank, I would also believe the store has weak stock.

+1

It doesn't sound like you're doing anything wrong. What species of cory are you going for? I'm finding some are more sensitive than others, and if they were wild caught, even more so.

It wouldn't surprise me if the girl at the store either didn't know when they came in, or lied about it. A lot of aquarists prefer to go for fish that have been there for a while since the weakest stock will have died off by then, so it wouldn't surprise me one bit if the policy of the store is to say they've been there for weeks so they'll get a sale. But I may just be cynical.

 

[Snowfire]

I guess it's impossible to know for sure how long the fish have been in the shop, I usually spend some time watching the fish before deciding which ones to buy but I guess it maybe isn't that easy...
The cories are bronze which I believe are some of the hardier ones.
The poorly one died shortly after I moved it to the hospital tank the remaining 2 are just sitting in the plants so I don't think they're very happy either.
Thanks for the words of encouragement everyone, it does make me feel a bit better about it!

 

[maestromad]

Just a thought do you have salt in te tank at all?? My cories hate salt and get very sluggish with that and if the temp is too high.
Keep the water fresh and I'm sure they will pull through

 

[KaylNeko]

Yes, the bronze are generally the hardier ones. However, there's a guy who has a journal up on another forum that finally gave up on bronze corys--they kept dying on him for no reason that anyone could come up with, so it's possible they've been bred so much and inbred that you've got some seriously weak strains out there. Either way, it sucks

 

[Snowfire]

I haven't ever put salt in the water, I know my black neons wouldn't like it either. Temp is about 24c so on the cool side if anything, should I warm it up a bit maybe?
I've just done a 25% pwc and put a bit of melafix in as well. I'm thinking it won't do any harm and might help with whatever is wrong. One of the two remaing is looking a bit sluggish now, the other one keeps nudging it to swim with him

 

[senemedar]

I haven't ever put salt in the water, I know my black neons wouldn't like it either. Temp is about 24c so on the cool side if anything, should I warm it up a bit maybe?
I've just done a 25% pwc and put a bit of melafix in as well. I'm thinking it won't do any harm and might help with whatever is wrong. One of the two remaing is looking a bit sluggish now, the other one keeps nudging it to swim with him

I know its a little bit off topic, but I just want to tell you that I know, how you feel-- I have the exact same problem with Guppies; no matter what tank I have and what I do, they always end up dead all of sudden, with no apparent signs of a disease (I just lost one last Friday)...